Curable composition and cured article

ABSTRACT

Provided are: a curable composition from which a cured article having excellent molding processability and high heat resistance as well as such a high Tg that it can be used as a molding resin for a SiC power semiconductor can be obtained; and a cured article thereof. The curable composition comprises: 100 parts by mass of a compound having at least two partial structures represented by the following Formula (1) in the molecule as a component (A); 0.5 to 3 parts by mass of a thermal radical generator as a component (B); and 0 to 50 parts by mass of other radical-reactive compound as a component (C): 
     
       
         
         
             
             
         
       
         
         
           
             (wherein, ring A represents a benzene ring or a cyclohexyl ring; R 1  represents an alkylene group having 1 to 6 carbon atoms; R 2  represents an alkyl group having 1 to 4 carbon atoms; a represents a number of 0 or 1; b represents an integer of 0 to 3; and c represents a number of 1 or 2).

TECHNICAL FIELD

The present invention relates to a curable composition and a curedarticle thereof. More particularly, the present invention relates to acurable composition from which a cured article having excellent moldingprocessability and high heat resistance can be obtained, and a curedarticle thereof.

BACKGROUND ART

SiC (silicon carbide) shows a lower electrical insulation and a smallerenergy loss at the time of electrification as compared to silicon andthus has a smaller calorific value as well as higher heat resistance.Therefore, as compared to silicon power semiconductors, SiC powersemiconductors are capable of handling a larger electric power, so thatSiC power semiconductors are being actively studied as next-generationpower semiconductors that would replace silicon power semiconductorsthat are widely used at present. The heat-resistance limit temperatureof silicon power semiconductor devices is about 150° C.; however, in SiCpower semiconductor devices, the use thereof at a temperature of 240 to300° C. is being investigated so as to handle a larger electric power,and heat resistance of higher than 240° C. is demanded also for themembers of SiC power semiconductor devices.

Conventionally, as a molding resin of a semiconductor obtained bymolding a resin, an epoxy resin is mainly used. In general, the physicalproperties of a resin, such as viscoelasticity and thermal expansioncoefficient, largely changes across its Tg (glass transitiontemperature); therefore, it is required that the Tg of a molding resinbe higher than the service temperature of the semiconductor. However,since the Tg of conventional epoxy resins is about 200° C. or lower,there are problems of material softening, crack generation and the likeunder such a service environment where the temperature exceeds 240° C.(see, for example, Patent Documents 1 and 2). In addition, since epoxyresins having a Tg of 240° C. or higher have high pre-curing meltingpoints, their curing temperatures are also high and curing requires along time, so that there are problems that other members are adverselyaffected and the productivity is reduced (see, for example, PatentDocument 3). Furthermore, although the use of resins other than epoxyresins, such as polyimide, has also been studied (see, for example,Patent Document 4), such resins are not satisfactory in terms ofrequired performance.

Meanwhile, curable compositions containing a vinylbenzyl ether compoundof a polyvalent phenol compound are also known (see, for example, PatentDocuments 5 to 7); however, all of these curable compositions have a Tgof lower than 240° C. and are thus not satisfactory as molding resins ofSiC powder semiconductors.

RELATED ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. 2005-036085-   Patent Document 2: Japanese Unexamined Patent Application    Publication No. 2006-269730-   Patent Document 3: Japanese Unexamined Patent Application    Publication No. 2011-184650-   Patent Document 4: Japanese Unexamined Patent Application    Publication No. 2010-222392-   Patent Document 5: Japanese Unexamined Patent Application    Publication No. 2000-258932-   Patent Document 6: Japanese Unexamined Patent Application    Publication No. 2004-189901-   Patent Document 7: Japanese Unexamined Patent Application    Publication No. 2010-202778

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Therefore, an object of the present invention is to provide a curablecomposition from which a cured article having excellent moldingprocessability and high heat resistance as well as such a high Tg thatit can be used as a molding resin for a SiC power semiconductor can beobtained; and a cured article thereof.

Means for Solving the Problems

In view of the above-described problems, the present inventorsintensively studied to discover that a curable composition comprising acompound having a specific structure has excellent moldingprocessability and high post-curing heat resistance, thereby completingthe present invention. That is, the present invention provides a curablecomposition which comprises: 100 parts by mass of a compound having atleast two partial structures represented by the following Formula (1) inthe molecule as a component (A); 0.5 to 3 parts by mass of a thermalradical generator as a component (B); and 0 to 50 parts by mass of otherradical-reactive compound as a component (C):

(wherein, ring A represents a benzene ring or a cyclohexyl ring; R¹represents an alkylene group having 1 to 6 carbon atoms; R² representsan alkyl group having 1 to 4 carbon atoms; a represents a number of 0 or1; b represents an integer of 0 to 3; and c represents a number of 1 or2).

In the curable composition according to the present invention, it ispreferred that the above-described component (A) be a compoundrepresented by the following Formula (2) or (3):

(wherein, R³ represents an alkyl group having 1 to 4 carbon atoms; drepresents an integer of 0 to 2; X¹ represents an oxygen atom, a sulfuratom, a sulfinyl group, a sulfonyl group, a carbonyl group, a phenylenegroup, a cyclohexylene group (however, 1,1-cyclohexylene group isexcluded), a group represented by the following Formula (4) or a directbond; and R¹, R², a, b and c have the same meanings as in the Formula(1))

(wherein, R⁴ and R⁵ each independently represent a hydrogen atom, atrifluoromethyl group or a hydrocarbon group having 1 to 12 carbonatoms, with a proviso that, when R⁴ and R⁵ are hydrocarbon groups having1 to 12 carbon atoms, R⁴ and R⁵ are optionally linked with each other)

(wherein, R′, R², a, b and c have the same meanings as in the Formula(1)).

It is also preferred that the curable composition according to thepresent invention further comprise a filler as a component (D).

The tablet for transfer molding according to the present invention iscomposed of the above-described curable composition.

The cured article according to the present invention is obtained bycuring the above-described curable composition.

The semiconductor element according to the present invention is obtainedby molding a cured article of the above-described curable composition.

Effects of the Invention

According to the present invention, a curable composition from which acured article having excellent molding processability and high heatresistance can be obtained and a cured article thereof can be provided.The curable composition of the present invention is useful particularlyas a molding material for semiconductors and the like.

MODE FOR CARRYING OUT THE INVENTION

The curable composition of the present invention is a curablecomposition which comprises: a compound having at least two partialstructures represented by the above-described Formula (1) in themolecule as a component (A); a radical generator as a component (B);and, optionally, other radical-reactive compound as a component (C).

First, the component (A) will be described. In the above-describedFormula (1), R′ represents an alkylene group having 1 to 6 carbon atoms.Examples of the alkylene group having 1 to 6 carbon atoms include amethylene group, an ethylene group, a propylene group, a butylene group,a pentylene group, a hexylene group, a 1-methylethylene group, a2-methylethylene group, a 2-methylpropylene group and a2,2-dimethylpropylene group. From the standpoint of the ease ofproduction, R¹ is preferably a methylene group. R² represents an alkylgroup having 1 to 4 carbon atoms and b represents an integer of 0 to 3.From the standpoint of the material availability, b is preferably 0.Examples of the alkyl group having 1 to 4 carbon atoms include a methylgroup, an ethyl group, a propyl group, an isopropyl group, a butylgroup, a 1-methylpropyl group, an isobutyl group and a t-butyl group.

In the above-described Formula (1), a represents a number of 0 or 1 andc represents a number of 1 or 2. From the standpoint of the ease ofproduction, a is preferably 1. Further, c is preferably 1 because goodstorage stability is attained and an abnormal reaction is not likely tooccur during a curing reaction of the curable composition of the presentinvention.

In the above-described Formula (1), the ring A represents a benzene ringor a cyclohexyl ring and, from the standpoint of improving the heatresistance, the ring A is preferably a benzene ring. The component (A)of the present invention is a compound having at least two partialstructures represented by the above-described Formula (1) in themolecule, in which the ring A or a part thereof is optionallyoverlapping. From the standpoint of reducing the thermal expansioncoefficient of the resulting cured article, it is preferred that thecomponent (A) of the present invention be a compound having two partialstructures represented by the above-described Formula (1) in themolecule.

The compound having at least two partial structures represented by theabove-described Formula (1) in the molecule can be rephrased as “acompound having at least two partial structures represented by thefollowing Formula (1a) in the molecule, in which the hydrogen atom ofthe hydroxyl group is substituted with a group represented by theFormula (1b)”:

(wherein, ring A has the same meaning as in the Formula (1))

(wherein, R¹, R², a, b and c have the same meanings as in the Formula(1)).

Among compounds having at least two partial structures represented bythe above-described Formula (1a) in the molecule, from the standpoint ofreducing the thermal expansion coefficient of the resulting curedarticle, those compounds that are represented by the following Formula(2a) or (3a) are more preferred:

(wherein, R³ represents an alkyl group having 1 to 4 carbon atoms; drepresents an integer of 0 to 2; X¹ represents an oxygen atom, a sulfuratom, a sulfinyl group, a sulfonyl group, a carbonyl group, a phenylenegroup, a cyclohexylene group (however, 1,1-cyclohexylene group isexcluded), a group represented by the following Formula (4) or a directbond)

(wherein, R⁴ and R⁵ each independently represent a hydrogen atom, atrifluoromethyl group or a hydrocarbon group having 1 to 12 carbonatoms, with a proviso that, when R⁴ and R⁵ are hydrocarbon groups having1 to 12 carbon atoms, R⁴ and R⁵ are optionally linked with each other).

In the above-described Formula (2a), R³ represents an alkyl group having1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbonatoms include the same groups as those exemplified for R² of theabove-described Formula (1) and, from the standpoint of attaining goodheat resistance, R³ is preferably a methyl group or a t-butyl group.Further, d represents an integer of 0 to 2 and, from the standpoint ofreducing the thermal expansion coefficient of a cured article obtainedfrom the curable composition of the present invention, d is preferably0. X¹ represents an oxygen atom, a sulfur atom, a sulfonyl group, asulfonyl group, a carbonyl group, a phenylene group, a cyclohexylenegroup (however, 1,1-cyclohexylene group is excluded), a grouprepresented by the above-described Formula (4) or a direct bond. Fromthe standpoint of reducing the thermal expansion coefficient of a curedarticle obtained from the curable composition of the present invention,it is preferred that the hydroxyl groups of the above-described Formula(2a) be each bound at para-position to X¹.

Examples of the phenylene group include a 1,2-phenylene group, a1,3-phenylene group and a 1,4-phenylene group. Examples of thecyclohexylene group (however, 1,1-cyclohexylene group is excluded)include 1,2-cyclohexylene group, 1,3-cyclohexylene group and1,4-cyclohexylene group.

In the above-described Formula (4), R⁴ and R⁵ each independentlyrepresent a hydrogen atom, a trifluoromethyl group or a hydrocarbongroup having 1 to 12 carbon atoms. However, when R⁴ and R⁵ arehydrocarbon groups having 1 to 12 carbon atoms, R⁴ and R⁵ are optionallylinked with each other. Examples of the group represented by the Formula(4) include the following groups:

Among those compounds represented by the above-described Formula (2a),examples of a compound in which X¹ is an oxygen atom includebis(2-hydroxyphenyl)ether and bis(4-hydroxyphenyl)ether.

Among those compounds represented by the above-described Formula (2a),examples of a compound in which X¹ is a sulfur atom, a sulfinyl group ora sulfonyl group include 2,4′-dihydroxydiphenyl sulfide,4,4′-dihydroxydiphenyl sulfide (also referred to as “bisphenol T”),4,4′-dihydroxydiphenyl sulfoxide, 2,2′-dihydroxydiphenyl sulfone,2,4′-dihydroxydiphenyl sulfone and 4,4′-dihydroxydiphenyl sulfone (alsoreferred to as “bisphenol S”).

Among those compounds represented by the above-described Formula (2a),examples of a compound in which X¹ is a carbonyl group include2,4′-dihydroxybenzophenone and 4,4′-dihydroxybenzophenone.

Among those compounds represented by the above-described Formula (2a),examples of a compound in which X¹ is a phenylene group include4,4′-(1,2-phenylene)bisphenol, 4,4′-(1,3-phenylene)bisphenol and4,4′-(1,4-phenylene)bisphenol.

Among those compounds represented by the above-described Formula (2a),examples of a compound in which X′ is a cyclohexylene group (however,1,1-cyclohexylene group is excluded) include4,4′-(1,2-cyclohexylene)bisphenol, 4,4′-(1,3-cyclohexylene)bisphenol and4,4′-(1,4-cyclohexylene)bisphenol.

Among those compounds represented by the above-described Formula (2a),examples of a compound in which X¹ is a direct bond includebiphenyl-2,2′-diol, biphenyl-2,4′-diol and biphenyl-4,4′-diol.

Among those compounds represented by the above-described Formula (2a),examples of a compound in which X¹ is a group represented by theabove-described Formula (4) include 2,2′-methylenebisphenol,2,4′-methylenebisphenol, 4,4′-methylenebisphenol,2,2′-ethylenebisphenol, 2,4′-ethylenebisphenol, 4,4′-ethylenebisphenol,4,4′-ethylidenebisphenol, 2,4′-isopropylidenebisphenol,4,4′-isopropylidenebisphcnol (also referred to as “bisphenol A”),4,4′-butylidenebisphenol, 4,4′-isobutylidenebisphenol,4,4′-sec-butylidenebisphenol (also referred to as “bisphenol B”),4,4′-isopropylidenebis(2-methylphenol) (also referred to as “bisphenolC”), 4,4′-(1,3-dimethylbutylidene)bisphenol (also referred to as “BisMIBK”), 4,4′-hexylidenebisphenol, 4,4′-(1-methylpentylidene)bisphenol,4,4′-(1-methylhexylidene)bisphenol, 4,4′-heptylidenebisphenol,4,4′-isopropylidenebis(2,6-dimethylphenol) (also referred to as“bisxylenol A”), 4,4′42-ethylhexylidene)bisphenol,4,4′-octylidenebisphenol, 4,4′-(1-methyloctylidene)bisphenol,4,4′-isopropylidenebis(3-t-butylphenol),4,4′-(1-phenylethylidene)bisphenol, 4,4′-(1-phenylethylidene)bisphenol(also referred to as “bisphenol AP”),4,4′-(1-phenylethylidene)bis(3-t-butylphenol),4,4′-(1-benzylethylidene)bisphenol,4,4′-(1-(4-methyl)phenylethylidene)bis(3-t-butylphenol),4,4′-(1-(4-phenyl)phenylethylidene)bis(3-t-butylphenol),4,4′-dihydroxytetraphenyl methane, 4,4′-cyclohexylidene diphenol,4,4′-(3,3,5-trimethylcyclohexylidene)diphenol,4,4′-(2-norbornylidene)diphenol,4,4′-(octahydro-4,7-methano-5H-indene-5-ylidene)bisphenol,4,4′-(indan-1-ylidene)diphenol, 4,4′-(3-phenylindan-1-ylidene)diphenol,4,4′-(fluorene-9-ylidene)diphenol and6,6′-dihydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobiindan.

Since a cured article having a high glass transition temperature can beobtained, among those compounds represented by the above-describedFormula (2a), ones in which X¹ is a sulfur atom, a sulfonyl group, aphenylene group, a group represented by the Formula (4) or a direct bondare preferred and, among those groups represented by the Formula (4),ones in which at least either of R⁴ and R⁵ is a hydrocarbon group havinga benzene ring are preferred.

Examples of a compound represented by the Formula (3a) includenaphthalene-1,2-diol, naphthalene-1,3-diol, naphthalene-1,4-diol,naphthalene-1,5-diol, naphthalene-1,6-diol, naphthalene-1,8-diol,naphthalene-2,3-diol, naphthalene-2,6-diol and naphthalene-2,7-diol. Itis noted here that the compound represented by the Formula (3a) is acompound in which a part of the ring A is overlapping.

Since a cured article having a high glass transition temperature can beobtained, among those compounds represented by the above-describedFormula (2a) or (3a), compounds represented by the Formula (2a) in whichX¹ is a sulfur atom, a sulfonyl group, a phenylene group, a grouprepresented by the Formula (4) or a direct bond or compounds representedby the Formula (3a) are preferred, and compounds represented by theFormula (2a) in which X′ is a group represented by the Formula (4) aremore preferred. Among such compounds represented by the Formula (2a) inwhich X¹ is a group represented by the Formula (4), ones in which atleast either of R⁴ and R⁵ is a hydrocarbon group having a benzene ringare preferred, and ones in which either R⁴ or R⁵ is a phenyl group andthe other is a methyl group are more preferred.

Among those compounds having at least two partial structures representedby the above-described Formula (1a) in the molecule, examples of acompound that is not a compound represented by the above-describedFormula (2a) or (3a) include cyclohexane ring-containing diol compoundssuch as 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol,4,4′-dicyclohexanediol, 2,2′-isopropylidene dicyclohexanol,4,4′-isopropylidene dicyclohexanol (also referred to as “hydrogenatedbisphenol A”), bicyclo[2,2,1]heptane-2,3-diol,bicyclo[2,2,1]heptane-2,5-diol, bicyclo[2,2,1]heptane-2,7-diol,octahydro-4,7-methano-1H-indene-5,6-diol, adamantane-1,3-diol,1,2,3,4-tetrahydronaphthalene-1,5-diol,1,2,3,4-tetrahydronaphthalene-5,8-diol and 1,5-decalindiol;

benzenediol compounds such as 1,2-benzenediol, 1,3-benzenediol,1,4-benzenediol and 2-methyl-1,3-benzenediol;

diphenol compounds such as 4,4′-(1,1,3-trimethyltrimethylene)bisphenol,3,4-bis(4-hydroxyphenyl)hexane, 1,3-bis(4-hydroxycumyl)benzene (alsoreferred to as “bisphenol M”), 1,4-bis(4-hydroxycumyl)benzene (alsoreferred to as “bisphenol P”), 4,4′-(phenylphosphinylidene)bisphenol,4,4′-(tetrafluoroisopropylidene)bisphenol (also referred to as“bisphenol AF”), 4,4′-isopropylidenebis(3,5-dibromophenol) (alsoreferred to as “tetrabromobisphenol A”), reaction product betweendicyclopentadiene and phenol, and 4,4′-oxybis(ethylenethio)diphenol;

triphenol compounds such as tris(4-hydroxyphenyl)methane (also referredto as “trisphenol PHBA”), 1,1,3-tris(4-hydroxyphenyl)propane (alsoreferred to as “trisphenol PA”),4,4′-[1-{4-(4-hydroxyphenylisopropylidene)phenyl}ethylidene]bisphenol,2,4,6-tris(4-hydroxyphenoxy)-1,3,5-triazine and2,4,6-tris(4-hydroxyphenyl)amino-s-triazine;

tetraphenol compounds such as 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane,1,4-bis[bis(4-hydroxyphenyl)methyl]benzene,1,4-bis[α,α-bis(4-hydroxyphenyl)benzyl]benzene,bis[4,4-bis(4-hydroxyphenyl)cyclohexane] andisopropylidene-bis[4,4-bis(4-hydroxyphenyl)cyclohexane];

naphthol compounds such as 1,1′-binaphthalene-2,2′-diol,2,2′-binaphthalene-1,1′-diol and 1,1′-thiobis-2-naphthol; phenol novolaccompounds; cresol novolac compounds; and hydroxystyrene oligomers.

Among these compounds, cyclohexane diol compounds and benzene diolcompounds are compounds in which the ring A is overlapping, and1,2,3,4-tetrahydronaphthalene-1,5-diol, 1,5-decalin diol and the likeare compounds in which the ring A is partially overlapping.

When the compound having two partial structures represented by theFormula (1a) in the molecule is a compound represented by theabove-described Formula (2a) or (3a), the component (A) of the curablecomposition of the present invention is a compound represented by thefollowing Formula (2) or (3):

(wherein, R¹, R², a, b and c have the same meanings as in the Formula(1); and R³, d and X¹ have the same meanings as in the Formula (2a))

(wherein, R¹, R², a, b and c have the same meanings as in the Formula(1)).

Next, a method of synthesizing the component (A) of the presentinvention will be described. The method of synthesizing the component(A) is not particularly restricted and, for example, in cases where a inthe above-described Formula (1) is 1, the component (A) may besynthesized by allowing a compound having at least two partialstructures represented by the above-described Formula (1a) in themolecule and a halogen compound represented by the following Formula(1c) to undergo an etherification reaction in accordance with theWilliamson method, which is a commonly used ether synthesis method:

(wherein, X² represents a halogen atom; and R¹, R², b and c have thesame meanings as in the Formula (1)).

In the Formula (1c), X² represents a halogen atom, and R¹, R², b and chave the same meanings as in the Formula (1). Examples of the halogenatom include a chlorine atom, a bromine atom and an iodine atom and,from the standpoints of good reactivity and material availability, X² ispreferably a chlorine atom or a bromine atom, more preferably a chlorineatom.

Next, the component (B) of the present invention, which is a thermalradical generator, will be described. In the present invention, the term“thermal radical generator” refers to a compound which generates aradical by the action of heat, and examples thereof include organicperoxide-based thermal radical generators and azo compound-based thermalradical generators.

Examples of the organic peroxide-based thermal radical generatorsinclude diisobutyryl peroxide, cumylperoxy neodecanoate,3-hydroxy-1,1-dimethylbutylperoxy neodecanoate, dipropylperoxydicarbonate, diisopropylperoxy dicarbonate, di-sec-butylperoxydicarbonate, 1,1,3,3-tetramethylbutylperoxy neodecanoate,bis(4-t-butylcyclohexyl)peroxy dicarbonate, bis(2-ethylhexyl)peroxydicarbonate, t-hexylperoxy neodecanoate, t-butylperoxy neodecanoate,t-butylperoxy neoheptanoate, t-heptylperoxy pivalate, t-butylperoxypivalate, t-pentylperoxy pivalate, bis(3,5,5-trimethylhexanoyl)peroxide,dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethyl hexanoate,disuccinic acid peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-pentylperoxy-2-ethyl hexanoate, t-butylperoxy-2-ethylhexanoate, 1,1-di(t-hexylperoxy)cyclohexane,1,1-di(t-butylperoxy)cyclohexane, 1,1-di(t-pentylperoxy)cyclohexane,2,2-bis(4,4-di(t-butylperoxy)cyclohexyl propane, t-hexylperoxyisopropylmonocarbonate, t-pentylperoxyisopropyl carbonate,t-pentylperoxy-n-octoate, t-butylperoxy maleate,1,1-di(t-butylperoxy)cyclohexane, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy laurate, t-butylperoxyisopropyl monohexanoate,t-pentylperoxy-2-ethylhexyl carbonate, t-butylperoxy-2-ethylhexylmonohexanoate, t-hexylperoxy benzoate, t-pentylperoxy acetate,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxy acetate,2,2-di(t-butylperoxy)butane, t-butylperoxy benzoate,butyl-4,4-di(t-butylperoxy)valerate,ethyl-3,3-di(t-butylperoxy)butyrate,bis(2-t-butylperoxyisopropyl)benzene, dicumyl peroxide, di-t-hexylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide,t-butylperoxy isobutyrate and 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

Examples of the azo compound-based thermal radical generators include2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(2-methylbutyronitrile),1,1′-azobis(cyclohexyl-1-carbonitrile),2,2′-azobis(N-(2-propyl)-2-methylpropionamide),1-((1-cyano-1-methylethyl)azo)formamide,2,2′-azobis(N-butyl-2-methylpropionamide),2,2′-azobis(N-cyclohexyl-2-methylpropionamide) and2,2′-azobis-isobutyronitrile.

From the standpoints of allowing the curable composition to have goodstorage stability and obtaining a cured article having a high Tg, it ispreferred that the component (B) of the present invention be an organicperoxide-based thermal radical generator. The organic peroxide-basedthermal radical generator may be appropriately selected in accordancewith the processing temperature of the curable composition of thepresent invention and, for example, in cases where the curablecomposition of the present invention is molded by transfer molding, theorganic peroxide-based thermal radical generator has a 1-minutehalf-life temperature of preferably 140 to 200° C., more preferably 150to 180° C.

In the curable composition of the present invention, the amount of thecomponent (B) to be blended is 0.5 to 3 parts by mass with respect to100 parts by mass of the component (A). When the amount of the component(B) is less than 0.5 parts by mass, a cured article having a high Tg maynot be obtained, while when the amount is greater than 3 parts by mass,the physical properties of the resulting cured article, such as hardnessand elasticity, may be adversely affected. The amount of the component(B) to be blended is preferably 0.6 to 2.5 parts by mass, morepreferably 0.7 to 2 parts by mass, most preferably 0.8 to 1.5 parts bymass, with respect to 100 parts by mass of the component (A).

Many of the compounds of the component (A) of the present invention havea high melting point, so that there may be a problem in terms of theworkability of the curable composition of the present invention.Therefore, in the curable composition of the present invention, in orderto lower its softening point, as a component (C), other radical-reactivecompound may also be incorporated in an amount of 0 to 50 parts by masswith respect to 100 parts by mass of the component (A). In the presentinvention, the term “other radical-reactive compound” refers to acompound which has radical reactivity and is different from the compoundof the component (A) that has at least two partial structuresrepresented by the above-described Formula (1) in the molecule. As suchother radical-reactive compound, a compound having at least tworadical-reactive groups, preferably ethylenically unsaturated bonds, inthe molecule is preferred since such a compound causes only a smallreduction in the mechanical and physical properties of the cured articleof the present invention.

Examples of compounds that are preferred as the component (C) includedivinylbenzene, trivinylbenzene, 2,3-divinyl naphthalene,2,3-divinylpyridine, diallyl phthalate, triallyl trimellitate,tetraallyl pyromellitate, diallyl tetrahydrophthalate, diallylhexahydrophthalate, 2,3-divinyl-2-cyclohexene-1-ol, diethylene glycolbis(allyl carbonate), trimethylolpropane diallyl ether,trimethylolpropane trimethacrylate, trimethylolpropane triacrylate,1,1,2,2-tetraallyloxy ethane, diallylidene pentaerythritol, triallylcyanurate, triallyl isocyanurate, glycidyldiallyl isocyanurate, diallylether of 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-divinylcyclohexane,1,2,4-trivinylcyclohexane, divinylbiphenyl, 1,3-diisopropenyl benzene,1,4-diisopropenyl benzene, 3,3′-diallyl bisphenol A,3,5,3′,5′-tetraallyl bisphenol A, 1,2-bis(dimethylvinylsilyl)benzene,1,3-bis(dimethylvinylsilyl)benzene, 1,4-bis(dimethylvinylsilyl)benzene,1,1,3,3-tetraphenyl-1,3-divinyl disiloxane and1,1,5,5-tetramethyl-3,3-diphenyl-1,5-divinyl trisiloxane. Thereamong,from the standpoint of allowing the curable composition of the presentinvention to have good storage stability and because of good reactivitywith the component (A), diallyl phthalate, triallyl trimellitate,tetraallyl pyromellitate, diallyl tetrahydrophthalate, diallylhexahydrophthalate, triallyl cyanurate, triallyl isocyanurate,glycidyldiallyl isocyanurate, 1,4-divinylcyclohexane,1,2,4-trivinylcyclohexane, 3,3′-diallyl bisphenol A,3,3′,5,5′-tetraallyl bisphenol A, 1,2-bis(dimethylvinylsilyl)benzene,1,3-bis(dimethylvinylsilyl)benzene, 1,4-bis(dimethylvinylsilyl)benzene,1,1,3,3-tetraphenyl-1,3-divinyl disiloxane and1,1,5,5-tetramethyl-3,3-diphenyl-1,5-divinyl trisiloxane triallylisocyanurate are preferred; diallyl phthalate, triallyl cyanurate,triallyl isocyanurate, 3,3′-diallyl bisphenol A, 3,3′,5,5′-tetraallylbisphenol A, 1,4-bis(dimethylvinylsilyl)benzene,1,1,3,3-tetraphenyl-1,3-divinyl disiloxane and1,1,5,5-tetramethyl-3,3-diphenyl-1,5-divinyl trisiloxane are morepreferred; and triallyl isocyanurate is most preferred.

The component (C) may be blended in such an amount that the curablecomposition of the present invention has a softening point at whichmolding thereof is easily carried out as long as the amount is 50 partsby mass or less with respect to 100 parts by mass of the component (A).When the amount of the component (C) is excessively large, the physicalproperties of the resulting cured article of the curable composition ofthe present invention may be deteriorated. Therefore, the amount of thecomponent (C) is preferably 0 to 30 parts by mass, more preferably 0 to20 parts by mass, with respect to 100 parts by mass of the component(A).

It is preferred that the curable composition of the present inventionfurther comprise a filler as a component (D) since it can improve themechanical strength, heat resistance and the like of the resulting curedarticle and reduce the thermal expansion coefficient. Examples of thefiller include silica-based inorganic fillers such as quartz, fumedsilica, precipitated silica, silicic acid anhydride, molten silica,crystalline silica and ultrafine powder amorphous silica; inorganiclayered substances such as magadiite, montmorillonite, saponite,kaolinite, ilerite and mica; fibrous fillers such as aramid fibers,silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers,metal fibers, glass fibers, alumina fibers and carbon fibers;nitride-based inorganic fillers such as silicon nitride, boron nitrideand aluminum nitride; metal oxide-based inorganic fillers such astitanium oxide, zinc oxide, zirconium oxide, niobium oxide, aluminumoxide, cerium oxide and yttrium oxide; carbon-based inorganic fillerssuch as silicon carbide, black lead, diamond, carbon blacks andgraphites; metal powders such as copper powder, aluminum powder, nickelpowder and silver powder; carbonates such as calcium carbonate,magnesium carbonate and dolomite; silicates such as alumina silicate andmagnesium silicate; sulfates such as calcium sulfate and barium sulfate;potassium titanate; barium titanate; aluminum borate; aluminumhydroxide; diatomaceous earth; white earth; clay; talc; wollastonite;zeolite; sericite; kaolin; pyrophyllite; bentonite; asbestos; glassbeads; glass flakes; and ceramic beads. Thereamong, from the standpointof obtaining a cured article having a low thermal expansion coefficient,silica-based inorganic fillers, aluminum oxide and aluminum nitride arepreferred; silica-based inorganic fillers are more preferred; and moltensilica is most preferred. The shape of the filler is preferablyspherical and the particle size is preferably in the range of 10 to 50μm since such a filler allows the curable composition of the presentinvention to have good fluidity.

When the amount of the component (D) contained in the curablecomposition of the present invention is excessively large, there may beadverse effects on the strength, bending elasticity and the like of thecured article of the present invention; therefore, the amount of thecomponent (D) to be contained is preferably 10 to 85 parts by mass, morepreferably 20 to 80 parts by mass, with respect to 100 parts by mass ofthe curable composition of the present invention.

In the curable composition of the present invention, in addition to thecomponents (A) to (D), an additive(s) imparting weather resistance,physical stability, mold-releasing property, storage stability and thelike can be used as well. Examples of such additives includeantioxidants, ultraviolet absorbers, hindered amine-based lightstabilizers, flame retardants, silane coupling agents and mold-releasingagents. In cases where such additive(s) is/are blended, the amountthereof can be appropriately selected in accordance with the intendedpurpose and the like of each additive; however, from the standpoint ofnot adversely affecting the effects of the present invention, the totalamount of all additives is preferably in the range of 10 parts by massor less with respect to 100 parts by mass of the curable composition ofthe present invention.

An antioxidant is an additive which inhibits oxidation and imparts heatresistance and weather resistance, and examples thereof includephenol-based antioxidants, phosphorus-based antioxidants andthioether-based antioxidants. Examples of the phenol-based antioxidantsinclude 2,6-di-t-butylphenol, 2,6-di-t-butyl-p-cresol,2,6-diphenyl-4-octadecyloxy phenol,distearyl(3,5-di-t-4-hydroxybenzyl)phosphonate,1,6-hexamethylenebis[(3,5-di-t-4-hydroxyphenyl)propionic acid amide],4,4′-thiobis(6-t-butyl-m-cresol),2,2′-methylenebis(4-methyl-6-t-butylphenol),2,2′-methylenebis(4-ethyl-6-t-butylphenol),4,4′-butylidenebis(6-t-butyl-m-cresol),2,2′-ethylidenebis(4,6-di-t-butylphenol),2,2′-ethylidenebis(4-sec-butyl-6-t-butylphenol),1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,1,3,5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)isocyanurate,1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate,1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,2-t-butyl-4-methyl-6-(2-acryloyloxy-3-t-butyl-5-methylbenzyl)phenol,stearyl(3,5-di-t-butyl-4-hydroxyphenyl)propionate, thiodiethyleneglycol-bis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate],1,6-hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate],bis[3,3-bis(4-hydroxy-3-t-butylphenyl)butyric acid]glycol ester,bis[2-t-butyl-4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl]terephthalate,1,3,5-tris[(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate,3,9-bis[1,1-dimethyl-2-{(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecaneand triethyleneglycol-bis[(3-t-butyl-4-hydroxy-5-methylphenyl)propionate].

Examples of the phosphorus-based antioxidants include[2-t-butyl-4-(3-t-butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite,tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenylphosphite, di(tridecyl)pentaerythritol diphosphite,di(nonylphenyl)pentaerythritol diphosphite,bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite,bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite,bis(2,4,6-tri-t-butylphenyl)pentaerythritol diphosphite,bis(2,4-dicumylphenyl)pentaerythritol di phosphite,tetra(tridecyl)isopropylidene diphenol diphosphite,tetra(tridecyl)-4,4′-n-butylidenebis(2-t-butyl-5-methylphenol)diphosphite,hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5t-butylphenyl)butanetriphosphite, tetrakis(2,4-di-t-butylphenyl)biphenylene diphosphonite,9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide,2,2′-methylenebis(4,6-t-butylphenyl)-2-ethylhexyl phosphite,2,2′-methylenebis(4,6-t-butylphenyl)-octadecyl phosphite,2,2′-ethylidenebis(4,6-di-t-butylphenyl)fluorophosphite, 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-t-butyl phenol.

Examples of the thioether-based antioxidants include dialkylthiodipropionates such as dilauryl thiodipropionate, dimyristylthiodipropionate and distearyl thiodipropionate; andβ-alkylmercaptopropionic acid esters of polyols, such as pentaerythritoltetra(β-dodecylmercaptopropionate).

The amount of the antioxidant(s) to be blended is preferably 0.001 to 10parts by mass, more preferably 0.05 to 5 parts by mass, with respect to100 parts by mass of the curable composition of the present invention.It is noted here that the phenol-based antioxidants also have an effectof improving the storage stability of the curable composition of thepresent invention.

An ultraviolet absorber is an additive which absorbs ultravioletradiation and imparts weather resistance, and examples thereof includebenzotriazole-based ultraviolet absorbers, triazine-based ultravioletabsorbers and benzophenone-based ultraviolet absorber.

Examples of the benzotriazole-based ultraviolet absorbers include2-(2′-hydroxy-5′-methylphenyl)benzotriazole,2-(2′-hydroxy-3′,5′-di-t-butylphenyl)-5-chlorobenzotriazole,2-(2′-hydroxy-3′-t-butyl-5′-methylphenyl)-5-chlorobenzotriazole,2-(2′-hydroxy-5′-t-octylphenyl)benzotriazole,2-(2′-hydroxy-3′,5′-dicumylphenyl)benzotriazole,2-(2′-hydroxy-3′-t-butyl-5′-carboxyphenyl)benzotriazole and2,2′-methylenebis(4-t-octyl-6-benzotriazolyl)phenol.

Examples of the triazine-based ultraviolet absorbers include2-(2-hydroxy-4-octoxyphenyl)-4,6-bis(2,4-dimethylphenyl)-s-triazine,2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl-s-triazine,2-(2-hydroxy-4-propoxy-5-methylphenyl)-4,6-bis(2,4-dimethylphenyl)-s-triazine,2-(2-hydroxy-4-hexyloxyphenyl)-4,6-dibiphenyl-s-triazine,2,4-bis(2-hydroxy-4-octoxyphenyl)-6-(2,4-dimethylphenyl)-s-triazine and2,4,6-tris(2-hydroxy-4-octoxyphenyl)-s-triazine.

Examples of the benzophenone-based ultraviolet absorbers include2,4-dihydroxy benzophenone, 2-hydroxy-4-methoxy benzophenone,2-hydroxy-4-octoxy benzophenone and5,5′-methylenebis(2-hydroxy-4-methoxybenzophenone).

The amount of the above-described ultraviolet absorber(s) to be blendedis preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 partsby mass, with respect to 100 parts by mass of the curable composition ofthe present invention.

A hindered amine-based light stabilizer is an additive which trapsradicals generated by ultraviolet radiation and the like and impartsweather resistance, and examples thereof include2,2,6,6-tetramethyl-4-piperidyl stearate,1,2,2,6,6-pentamethyl-4-piperidyl stearate,2,2,6,6-tetramethyl-4-piperidyl benzoate,bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate,bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate,bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate,1,2,2,6,6-pentamethyl-4-piperidyl methacrylate,2,2,6,6-tetramethyl-piperidyl methacrylate,tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate,tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate,bis(2,2,6,6-tetramethyl-4-piperidyl).bis(tridecyl)-1,2,3,4-butanetetracarboxylate,bis(1,2,2,6,6-pentamethyl-4-piperidyl).bis(tridecyl)-1,2,3,4-butanetetracarboxylate,bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-t-butyl-4-hydroxybenzyl)malonate,3,9-bis[1,1-dimethyl-2-[tris(2,2,6,6-tetramethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane,3,9-bis[1,1-dimethyl-2-[tris(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane,1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/2,4-dichloro-6-morpholino-s-triazinepolycondensate,1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/2,4-dichloro-6-t-octylamino-s-triazinepolycondensate,1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidypamino)-s-triazine-6-yl]-1,5,8,12-tetraazadodecane,1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazine-6-yl]-1,5,8,12-tetraazadodecane,1,6,11-tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazine-6-ylamino]undecane,1,6,11-tris[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidypamino)-s-triazine-6-ylamino]undecane,1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol/diethylsuccinatepolycondensate and1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane/dibromoethanepolycondensate.

The amount of the above-described hindered amine-based lightstabilizer(s) to be blended is preferably 0.001 to 10 parts by mass withrespect to 100 parts by mass of the curable composition of the presentinvention.

A flame retardant is an additive which imparts flame retardancy to aresin. Examples thereof include phosphate compounds such as triphenylphosphate, phenol-resorcinol-phosphorus oxychloride condensate,phenol-bisphenol A-phosphorus oxychloride condensate and2,6-xylenol-resorcinol-phosphorus oxychloride condensate; phosphoricacid amide compounds such as aniline-phosphorus oxychloride condensateand phenol-xylylene diamine-phosphorus oxychloride condensate;phosphazenes; halogen-based flame retardants such as decabromodiphenylether and tetrabromobisphenol A; phosphates of nitrogen-containingorganic compounds, such as melamine phosphate, piperazine phosphate,melamine pyrophosphate, piperazine pyrophosphate, melamine polyphosphateand piperazine polyphosphate; red phosphorus and surface-treated ormicrocapsulated red phosphorus; flame retardant aids such as antimonyoxide and zinc borate; and anti-drip agents such aspolytetrafluoroethylenes and silicon resins.

The amount of the flame retardant(s) to be blended is preferably 2 to 20parts by mass, more preferably 5 to 10 parts by mass, with respect to100 parts by mass of the curable composition of the present invention.

A silane coupling agent is a component which improves the adhesivenessof the resulting cured article. Examples thereof include3-chloropropyltrimethoxysilane, vinyltrichlorosilane,vinyltriethoxysilane, vinyl-tris-(2-methoxyethoxy)silane,3-methacryloxypropyltrimethoxysilane,2-(3,4-ethoxycyclohexyl)ethyltrimethoxysilane,3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane,3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane andN-2-(aminoethyl)-3-aminopropyltrimethoxy silane.

The amount of the silane coupling agent(s) to be blended is preferably0.01 to 5 parts by mass, more preferably 0.1 to 2 parts by mass, withrespect to 100 parts by mass of the curable composition of the presentinvention.

A mold-releasing agent is a component which improves the mold-releasingfrom a die at the time of molding. Examples thereof include carnaubawax, montanoic acid, higher fatty acids such as stearic acid, metalsalts of higher fatty acids, ester-based waxes such as montanic acidester, oxidized polyolefin-based waxes such as oxidized polyethylene,and non-oxidized polyolefin-based waxes such as non-oxidizedpolyethylene. These mold-releasing agents may be used individually, ortwo or more thereof may be used in combination. Among thesemold-releasing agents, it is preferred to use an oxidizedpolyolefin-based wax or a non-oxidized polyolefin-based wax in an amountof 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass,with respect to 100 parts by mass of the curable composition of thepresent invention.

The curable composition of the present invention can be cured by anactive energy beam such as ultraviolet radiation, electron beam, X-ray,radiation or high-frequency wave when a photoradical generator is usedas the component (B) or by heating when a thermal radical generator isused as the component (B). It is preferred that the curable compositionof the present invention be cured by heating since it has excellentmolding processability into a three-dimensional molded article. Variouscuring temperatures can be set by selecting the type of the thermalradical generator; however, when the curing temperature is excessivelylow, the storage stability of the curable composition of the presentinvention may become poor and there may arise a problem in theworkability due to an increase in the time required for curing, whilewhen the curing temperature is excessively high, the dimensionalaccuracy of molding in the present invention may become poor. Therefore,the curing temperature of the curable composition of the presentinvention is preferably 100 to 250° C., more preferably 150 to 200° C.

The curable composition of the present invention can be molded by amolding method known as a method of molding a thermosetting resin, suchas compression molding, transfer molding, injection molding, extrusionmolding, casting or RIM molding. Thereamong, transfer molding ispreferred since the curable composition of the present invention hasexcellent molding processability into a three-dimensional object.Further, the curable composition of the present invention, after beingcured, may also be subjected to post-curing (after-curing) as required.By performing post-curing, a curing reaction proceeds further, so thatthe physical strength and heat resistance of the resulting cured articleof the curable composition of the present invention are improved.

In cases where the curable composition of the present invention ismolded by transfer molding, the curable composition of the presentinvention may be used as is; however, it is preferably processed into atablet before use since thereby air bubbles are less likely to beentrapped and a good-quality cured article can be obtained. In caseswhere the curable composition of the present invention is processed intoa tablet, the components of the curable composition of the presentinvention may be loaded all together to a dissolving bath and thenmelt-mixed batchwise, or the components may be loaded all together to akneader such as a heated 3-roll mill and then melt-mixed continuously.The shape of the tablet is not particularly restricted and it may beadjusted to the specifications of the transfer molding machine in whichthe curable composition of the present invention is used.

The curable composition of the present invention is excellent in termsof molding processability, particularly molding processability intransfer molding. The curable composition of the present invention canthus be suitably used as a molding material for a semiconductor element.Examples of a semiconductor element in which the curable composition ofthe present invention is suitably used include integrated circuits suchas ICs and LSIs; optical semiconductor elements such as light-emittingdiodes (LEDs), organic electroluminescent elements (organic ELs), laserdiodes, LED arrays and CCDs; and SiC power semiconductors. Since a curedarticle of the curable composition of the present invention has highheat resistance, it is particularly preferably used as a moldingmaterial for a power semiconductor or power module where high-level heatresistance is required, particularly as a molding material for a SiCpower semiconductor or SiC power module. Examples of a powersemiconductor in which the curable composition of the present inventionis used as a molding material include GTO (Gate Turn Off) thyristors,insulated gate bipolar transistors (IGBTs), metal oxide semiconductorfield-effect transistors (MOSFETs), static induction transistors (SITs),diodes, power transistors, thyristors and triacs. Further, examples of apower module include general-purpose inverter modules, IPMs (IntelligentPower Modules) and inverter modules for automobiles. These powersemiconductors and power modules can be used in railcars, heavy electricplants, hybrid cars, electric cars, robot welders, elevators, airconditioners, uninterruptible power supplies (UPS), general-purposeinverters (control units of general-purpose motors), washing machines,microwave ovens, electromagnetic ranges, electric fans, refrigerators,electric rice-cookers, VTRs, audio instruments and the like.

In addition to the above, the curable composition of the presentinvention can also be suitably used, for example, as an insulatingmaterial of a semiconductor element and a substrate of a printed circuitboard or the like, as well as in the chassis and parts of electricalproducts and electrical/electronic equipments and parts of automobiles,railcars, airplanes and the like.

EXAMPLES

The present invention will now be described in more detail by way ofexamples and comparative examples thereof. However, the presentinvention is not restricted thereto by any means. It is noted here that,in the following Examples, “part(s)” and “%” are based on mass unlessotherwise specified.

Production Example 1 Synthesis of Compound A1

To a glass reaction vessel equipped with an agitator, a thermometer, anitrogen-introducing tube, a dropping funnel and a condenser tube, 549 gof 4,4′-(1-phenylethylidene)bisphenol (1.89 mol, manufactured by HonshuChemical Industry Co., Ltd.), 1.4 kg of methanol, 266 g (4.75 mol) ofpotassium hydroxide and 691 g (4.53 mol) of chloromethylstyrene wereadded and stirred at 60° C. for 1 hour. Then, after terminating thestirring, the resultant was allowed to separate into two layers and thelower layer was removed. The upper layer was cooled and purified byrecrystallization to obtain 613 g of a compound A1 as white solid(yield: 62%). The thus obtained compound A1 had the following structureand a melting point of 102° C.

Production Example 2 Synthesis of Compound A2

A compound A2 was obtained as white solid by performing the sameoperations as in Production Example 1, except that biphenyl-2,2′-diolwas used in place of 4,4′-(1-phenylethylidene)bisphenol. The thusobtained compound A2 had the following structure and a melting point of98° C.

Production Example 3 Synthesis of Compound A3

A compound A3 was obtained as white solid by performing the sameoperations as in Production Example 1, except that 1,6-naphthalene diolwas used in place of 4,4′-(1-phenylethylidene)bisphenol. The thusobtained compound A3 had the following structure and a melting point of122° C.

Production Example 4 Synthesis of Compound A4

A compound A4 was obtained as white solid by performing the sameoperations as in Production Example 1, except that4,4′-dihydroxydiphenyl sulfide was used in place of4,4′-(1-phenylethylidene)bisphenol. The thus obtained compound A4 hadthe following structure and a melting point of 170° C.

Production Example 5 Synthesis of Compound A5

A compound A5 was obtained as white solid by performing the sameoperations as in Production Example 1, except that4,4′-dihydroxydiphenyl sulfone was used in place of4,4′-(1-phenylethylidene)bisphenol. The thus obtained compound A5 hadthe following structure and a melting point of 121° C.

Curable Resin Components for Comparison

a1: epoxy resin (manufactured by Sigma-Aldrich Co. LLC,poly[(o-cresylglycidylether)-CO-formaldehyde], number-average molecularweight (Mn): ˜870)

a2: phenol resin (manufactured by Gun Ei Chemical Industry Co., Ltd.,trade name: PSM4326)

Component (B)

B1: dicumyl peroxide (manufactured by NOF Corporation, trade name:PERCUMYL D)

Component (C)

C1: triallyl isocyanurate (manufactured by Nippon Kasei Chemical CompanyLimited, trade name: TAIC)

Component (D)

D1: spherical silica (manufactured by Tokuyama Corporation, trade name:SE-40, average particle size: 40 μm)

D2: spherical silica (manufactured by Admatechs Company Limited, tradename: SO-E5, average particle size: 15 μm)

D3: molten silica (manufactured by DENKI KAGAKU KOGYO KABUSHIKI KAISHA,trade name: FB-950, average particle size: 24 μm)

Antioxidant

E1: 2,6-di-t-butyl phenol

[Tablet Preparation]

Using the thus obtained compounds A1 to A5 and the above-describedcompounds, tablets having the respective formulations shown in Table 1and 2 were prepared by the following steps. It is noted here that, inthese Tables, all numerical values are based on parts by mass.

(1) Melt-mixing the components other than the components (B) and (D).

(2) Using a mixer, knead the resulting mixture and the components (B)and (D) at 100° C. for 30 minutes.

(3) Cool and pulverize the kneaded product.

(4) Using a tablet machine (manufactured by Oji Kikai Co., Ltd.,OTM-10-80), mold the resultant into a tablet of 15 mm in diameter and 18mm in height (mass: about 25 g).

TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 A1 100 100 100 100 100 50 — 70 — —A2 — — — — — 50 — — — — A3 — — — — — — 100 — — — A4 — — — — — — — 30 5050 A5 — — — — — — — — 50 50 B1 1.1 0.7 2.2 1.1 1.1 1.1 1.1 1.1 1.1 0.6C1 11 11 11 11 — — 11 11 11 11 D1 444 444 444 — — — — — — — D2 185 185185 — — — — — — — D3 — — — — 604 604 604 604 604 604 E1 — — 0.3 0.3 0.30.3 0.3 0.3 0.3 —

TABLE 2 Comparative Example 1 2 3 4 5 6 A1 — — 100 100 100 — A4 — — — —— 50 A5 — — — — — 50 a1 100 100 — — — — a2 36 36 — — — — B1 — — 0.1 0.40.3 0.3 C1 545 — 11 11 — 11 D1 227 — 444 444 — — D2 — 741 185 185 — — D3— — — — 604 604 E1 — — — — 0.3 —[Spiral Flow]

Using a transfer molding machine (manufactured by Kodaira SeisakushoCo., Ltd., model: SP-T-10), the spiral flow length of each tablet wasmeasured under the following conditions. The results thereof are shownin Table 3 and 4.

Die: spiral flow die (semicircular with a cross-sectional radius of 2.5mm)

Extrusion pressure: 10 MPa

Die temperature: 130° C.

Injection time: 10 seconds

[Preparation of Test Piece]

Using a transfer molding machine (manufactured by Kodaira SeisakushoCo., Ltd., model: SP-T-10), each tablet was transfer-molded under thefollowing conditions to prepare a test piece of 100 mm in length, 35 mmin width and 2 mm in thickness.

Injection Conditions

Extrusion pressure: 10 MPa

Die temperature: 130° C.

Injection time: 2 minutes

Curing Conditions

Die temperature: 150° C.

Curing time: 5 minutes

Post-curing

250° C., 30 minutes

Under the below-described conditions, the heat resistance (residualweight ratio and bending modulus), linear thermal expansion coefficient,glass transition temperature and 5% weight reduction temperature weremeasured. The results thereof are shown in Table 3 and 4.

[Heat Resistance]

The thus obtained test pieces were each stored under an atmosphere in a250° C. oven for 100 hours and 300 hours. Before the storage in the oven(0 hr), after 100 hours of storage (100 hr) and after 300 hours ofstorage (300 hr), the residual weight ratio and the bending modulus ofeach test piece were measured by the below-described methods.

[Residual Weight Ratio]

The mass of each test piece was measured before the storage in the oven,after 100 hours of storage and after 300 hours of storage and it wasexpressed in percentage, taking the mass of each test piece before thestorage in the oven as 100%.

[Bending Modulus]

In accordance with JIS K6911 (Testing methods for thermosettingplastics), the bending modulus was measured using a resin universaltester (manufactured by SHIMADZU CORPORATION, model: AUTOGRAPH AG-X).

[Linear Thermal Expansion Coefficient and Glass Transition Temperature]

Using a thermomechanical analyzer (manufactured by SII NanoTechnologyInc., model: EXSTAR TMA/SS 6100), the linear thermal expansioncoefficient and the glass transition temperature were measured.

[5% Weight Reduction Temperature]

After collecting 1 part of each test piece, the 5% weight reductiontemperature thereof was measured under the following conditions using adifferential thermogravimetric simultaneous measurement apparatus(manufactured by SII NanoTechnology Inc., model: EXSTAR TG/DTA 6300).

Measurement atmosphere: in the air

Initial heating temperature: 100° C.

Heating rate: 10° C./minute

Final heating temperature: 550° C.

TABLE 3 Example 1 2 3 4 5 6 7 8 9 10 Spiral flow (cm) 104 104103 >150 >150 >150 98 90 110 110 Glass transitiontemperature >300 >300 >300 >300 >300 >300 >300 >300 >300 >300 (° C.)Linear thermal α1*¹ 11 11 11 75 11 16 15 15 14 14 expansion coefficientα2*² — — — — — — — — — — (ppm/K) 5% weight reduction 490 492 485 425 458515 527 513 519 519 temperature (° C.) Heat Residual  0 hr 100 100 100100 100 100 100 100 100 100 resistance weight 100 hr 99.9 99.9 99.9 98.899.9 99.9 99.9 99.9 99.9 99.9 (%) 300 hr 99.7 99.8 99.5 98.0 99.8 99.799.7 99.7 99.8 99.8 Bending  0 hr 26 26 26 3.5 25 26 28 27 24 24 modulus100 hr 27 27 27 3.5 26 26 28 28 24 24 (GPa) 300 hr 28 28 29 3.5 26 28 2929 25 25 *¹α1 = Linear thermal expansion coefficient before reaching theglass transition temperature *²α2 = Linear thermal expansion coefficientafter reaching the glass transition temperature

TABLE 4 Comparative Example 1 2 3 4 5 6 Spiral flow (cm) 100 >150 104104 >150 110 Glass transition temperature (° C.) 124 126 208 221 218 229Linear thermal expansion α1*¹ 18 19 12 12 76 15 coefficient (ppm/K) α2*²61 64 54 53 109 55 5% weight reduction temperature (° C.) 459 455 482485 412 488 Heat Residual weight  0 hr 100 100 100 100 100 100resistance (%) 100 hr 99.5 99.4 99.8 99.8 98.8 99.9 300 hr 98.7 98.599.5 99.6 98.0 99.8 Bending  0 hr 21 20 24 25 3.5 24 modulus 100 hr 2120 25 26 3.5 24 (GPa) 300 hr 15 14 27 27 3.5 25 *¹α1 = Linear thermalexpansion coefficient before reaching the glass transition temperature*²α2 = Linear thermal expansion coefficient after reaching the glasstransition temperature

As clearly seen from Table 3, it was confirmed that the cured articlesof the curable composition according to the present invention had aspiral flow equal to or higher than those of the comparative epoxy resincompositions and thus had a higher fluidity at the time of heat moldingas well as superior productivity. In addition, the cured articlesaccording to the present invention had a high residual weight ratio, alow linear expansion coefficient and a high glass transitiontemperature. From comparisons between Example 4 and other Examples, itwas revealed that, by incorporating a filler into the curablecomposition of the present invention, the linear thermal expansioncoefficient and the heat resistance are markedly improved. The curedarticles of the present inventions have a glass transition temperatureof 300° C. or higher; therefore, they can also be suitably used in SiCpower semiconductors that may possibly be used at a high temperature ofabout 300° C. On the other hand, as clearly seen from the results ofComparative Examples 1, 2 and 3 to 6, a sufficient glass transitiontemperature was not attained in conventional epoxy resin compositionsand those curable compositions in which the component (A) according tothe present invention was used but the amount of the component (B) wasless than a prescribed value.

The invention claimed is:
 1. A curable composition, comprising: acompound having a structure represented by the following Formula (2) asa component (A); a thermal radical generator as a component (B); andother radical-reactive compound as a component (C), wherein Formula (2)is represent by:

wherein, R¹ represents an alkylene group having 1 to 6 carbon atoms; crepresents a number of 1 or 2; R³ represents an alkyl group having 1 to4 carbon atoms; d represents an integer of 0 to 2; X¹ represents anoxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, acarbonyl group, a phenylene group, a cyclohexylene group (however,1,1-cyclohexylene group is excluded), a group represented by thefollowing Formula (4) or a direct bond;

wherein, R⁴ and R⁵ each independently represent a hydrogen atom, atrifluoromethyl group or a hydrocarbon group having 1 to 12 carbonatoms, with a proviso that, when R⁴ and R⁵ are hydrocarbon groups having1 to 12 carbon atoms, R⁴ and R⁵ are optionally linked with each other,wherein component (C) is selected from the group consisting of diallylphthalate, triallyl trimellitate, tetraallyl pyromellitate, diallyltetrahydrophthalate, diallyl hexahydrophthalate, triallyl cyanurate,triallyl isocyanurate, glycidyldiallyl isocyanurate1,4-divinylcyclohexane, 1,2,4-trivinylcyclohexane, 3,3′-diallylbisphenol A, 3,3′,5,5′-tetraallyl bisphenol A,1,2-bis(dimethylvinylsilyl)benzene, 1,3-bis(dimethylvinylsilyl)benzene,1,4-bis(dimethylvinylsilyl)benzene, 1,1,3,3-tetraphenyl-1,3-divinyldisiloxane and 1,1,5,5-tetramethyl-3,3-diphenyl-1,5-divinyl trisiloxanetriallyl isocyanurate, wherein an amount of component (B) is 0.5 to 3parts by mass with respect to 100 parts by mass of component (A),wherein an amount of component (C) is 11 to 50 parts by mass withrespect to 100 parts by mass of component (A).
 2. The curablecomposition according to claim 1, which further comprises a filler as acomponent (D).
 3. A tablet for transfer molding, which is composed ofthe curable composition according to claim
 1. 4. A cured article, whichis obtained by curing the curable composition according to claim
 1. 5. Asemiconductor element, which is obtained by molding a cured article ofthe curable composition according to claim
 1. 6. A tablet for transfermolding, which is composed of the curable composition according to claim2.
 7. A cured article, which is obtained by curing the curablecomposition according to claim
 2. 8. A semiconductor element, which isobtained by molding a cured article of the curable composition accordingto claim
 2. 9. The curable composition according to claim 1, wherein X¹represents an oxygen atom, a sulfur atom, a sulfonyl group, a sulfonylgroup, a carbonyl group, or a cyclohexylene group (however,1,1-cyclohexylene group is excluded).